package com.besttone.widget.scroll;

import android.R.bool;
import android.content.Context;
import android.util.AttributeSet;
import android.util.Log;
import android.view.MotionEvent;
import android.view.VelocityTracker;
import android.view.View;
import android.view.ViewConfiguration;
import android.view.ViewGroup;
import android.view.View.MeasureSpec;
import android.widget.Scroller;

public class MyScrollLayout extends ViewGroup{

    private static final String TAG = "ScrollLayout";   
    
    private VelocityTracker mVelocityTracker;  			// 用于判断甩动手势
    
    private static final int SNAP_VELOCITY = 600;    
    
    private Scroller  mScroller;						// 滑动控制器
	
    private int mCurScreen;    						
    
	public int getmCurScreen() {
		return mCurScreen;
	}

	private int mDefaultScreen = 0;    					
	 
    private float mLastMotionX;    
    
    private int mTouchSlop;							
    
    private static final int TOUCH_STATE_REST = 0;
    private static final int TOUCH_STATE_SCROLLING = 1;
    private int mTouchState = TOUCH_STATE_REST;
    
    private OnViewChangeListener mOnViewChangeListener;

private boolean bScroll=false;
	 
	public MyScrollLayout(Context context) {
		super(context);
		// TODO Auto-generated constructor stub
		init(context);
	}
	
	public MyScrollLayout(Context context, AttributeSet attrs) {
		super(context, attrs);
		// TODO Auto-generated constructor stub
		init(context);
	}
	
	public MyScrollLayout(Context context, AttributeSet attrs, int defStyle) {
		super(context, attrs, defStyle);
		// TODO Auto-generated constructor stub
		
		init(context);
	}
	
	private void init(Context context)
	{
		mCurScreen = mDefaultScreen;    
	  
	 //   mTouchSlop = ViewConfiguration.get(getContext()).getScaledTouchSlop();    
	        
	    mScroller = new Scroller(context); 
	    
	}

	@Override
	protected void onLayout(boolean changed, int l, int t, int r, int b) {
		// TODO Auto-generated method stub
		
		
		 if (changed) {    
	            int childLeft = 0;    
	            final int childCount = getChildCount();    
	                
	            for (int i=0; i<childCount; i++) {    
	                final View childView = getChildAt(i);    
	                if (childView.getVisibility() != View.GONE) {    
	                    final int childWidth = childView.getMeasuredWidth();    
	                    childView.layout(childLeft, 0,     
	                            childLeft+childWidth, childView.getMeasuredHeight());    
	                    childLeft += childWidth;    
	                }    
	            }    
	        }    
	}

	@Override
	protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
		// TODO Auto-generated method stub
		super.onMeasure(widthMeasureSpec, heightMeasureSpec);
		
	
		
		final int width = MeasureSpec.getSize(widthMeasureSpec);       
	    final int widthMode = MeasureSpec.getMode(widthMeasureSpec);      
	    
		
		final int count = getChildCount();       
        for (int i = 0; i < count; i++) {       
            getChildAt(i).measure(widthMeasureSpec, heightMeasureSpec);       
        }         
        
        scrollTo(mCurScreen * width, 0);
		
	}


	 public void snapToDestination() {    
	        final int screenWidth = getWidth();    

	        final int destScreen = (getScrollX()+ screenWidth/2)/screenWidth;    
	        snapToScreen(destScreen);    
	 }  
	
	 public void snapToScreen(int whichScreen) {    
	
	        // get the valid layout page    
	        whichScreen = Math.max(0, Math.min(whichScreen, getChildCount()-1));    
	        if (getScrollX() != (whichScreen*getWidth())) {    
	                
	            final int delta = whichScreen*getWidth()-getScrollX();    
	        
	            mScroller.startScroll(getScrollX(), 0,     
	                    delta, 0, Math.abs(delta)*2);
 
	            
	            mCurScreen = whichScreen;    
	            invalidate();       // Redraw the layout    
	            
	            if (mOnViewChangeListener != null)
	            {
	            	mOnViewChangeListener.OnViewChange(mCurScreen);
	            }
	        }    
	    }    


	@Override
	public void computeScroll() {
		// TODO Auto-generated method stub
		if (mScroller.computeScrollOffset()) {    
            scrollTo(mScroller.getCurrX(), mScroller.getCurrY());  
            postInvalidate();    
        }   
	}

	@Override
	public boolean onTouchEvent(MotionEvent event)
	{
		// TODO Auto-generated method stub

		final int action = event.getAction();
		final float x = event.getX();
		final float y = event.getY();

		switch (action)
		{
			case MotionEvent.ACTION_DOWN:

				Log.i("onTouchEvent", "ACTION_DOWN");

				if (mVelocityTracker == null)
				{
					mVelocityTracker = VelocityTracker.obtain();
					mVelocityTracker.addMovement(event);
				}

				if (!mScroller.isFinished())
				{
					mScroller.abortAnimation();
				}

				mLastMotionX = x;
				break;

			case MotionEvent.ACTION_MOVE:
				int deltaX = (int) (mLastMotionX - x);
				if (deltaX > 1)
					bScroll = true;
				if (IsCanMove(deltaX))
				{
					if (mVelocityTracker != null)
					{
						mVelocityTracker.addMovement(event);
					}

					Log.i("onTouchEvent", "ACTION_MOVE");
					mLastMotionX = x;

					scrollBy(deltaX, 0);
				}

				break;

			case MotionEvent.ACTION_UP:
				if (!bScroll)
				{
					boolean result = performClick();
				}
				bScroll = false;
				int velocityX = 0;
				if (mVelocityTracker != null)
				{
					mVelocityTracker.addMovement(event);
					mVelocityTracker.computeCurrentVelocity(1000);
					velocityX = (int) mVelocityTracker.getXVelocity();
				}

				if (velocityX > SNAP_VELOCITY && mCurScreen > 0)
				{
					// Fling enough to move left
					// Log.e(TAG, "snap left");
					snapToScreen(mCurScreen - 1);
				}
				else if (velocityX < -SNAP_VELOCITY && mCurScreen < getChildCount() - 1)
				{
					// Fling enough to move right
					// Log.e(TAG, "snap right");
					snapToScreen(mCurScreen + 1);
				}
				else
				{
					snapToDestination();
				}

				if (mVelocityTracker != null)
				{
					mVelocityTracker.recycle();
					mVelocityTracker = null;
				}

				// mTouchState = TOUCH_STATE_REST;
				break;
		}

		return true;
	}
	
	@Override
	public boolean onInterceptTouchEvent(MotionEvent ev)
	{
		// TODO Auto-generated method stub
		final int action = ev.getAction();
		final float x = ev.getX();
		final float y = ev.getY();

		switch (action)
		{
			case MotionEvent.ACTION_DOWN:

				Log.i("onInterceptTouchEvent", "ACTION_DOWN");

				if (mVelocityTracker == null)
				{
					mVelocityTracker = VelocityTracker.obtain();
					mVelocityTracker.addMovement(ev);
				}

				if (!mScroller.isFinished())
				{
					mScroller.abortAnimation();
				}

				mLastMotionX = x;
				break;

			case MotionEvent.ACTION_MOVE:
				int deltaX = (int) (mLastMotionX - x);
//				if (deltaX > 1)
//					bScroll = true;
				if (IsCanMove(deltaX))
				{
					if (mVelocityTracker != null)
					{
						mVelocityTracker.addMovement(ev);
					}

					mLastMotionX = x;
					Log.i("onInterceptTouchEvent", "ACTION_MOVE");
//					Log.i("ACTION_MOVE", "  deltaX="+deltaX);
					scrollBy(deltaX, 0);
				}

				break;

			case MotionEvent.ACTION_UP:
//				if (!bScroll)
//				{
//					boolean result = performClick();
//				}
//				bScroll = false;
				int velocityX = 0;
				if (mVelocityTracker != null)
				{
					mVelocityTracker.addMovement(ev);
					mVelocityTracker.computeCurrentVelocity(1000);
					velocityX = (int) mVelocityTracker.getXVelocity();
				}

				if (velocityX > SNAP_VELOCITY && mCurScreen > 0)
				{
					// Fling enough to move left
					// Log.e(TAG, "snap left");
					snapToScreen(mCurScreen - 1);
				}
				else if (velocityX < -SNAP_VELOCITY && mCurScreen < getChildCount() - 1)
				{
					// Fling enough to move right
					// Log.e(TAG, "snap right");
					snapToScreen(mCurScreen + 1);
				}
				else
				{
					snapToDestination();
				}

				if (mVelocityTracker != null)
				{
					mVelocityTracker.recycle();
					mVelocityTracker = null;
				}

				// mTouchState = TOUCH_STATE_REST;
				break;
		}

//		switch (action)
//		{
//			case MotionEvent.ACTION_MOVE:
//				final int xDiff = (int) Math.abs(mLastMotionX - x);
//				if (xDiff > mTouchSlop)
//				{
//					mTouchState = TOUCH_STATE_SCROLLING;
//				}
//				break;
//
//			case MotionEvent.ACTION_DOWN:
//				mLastMotionX = x;
//
//				mTouchState = mScroller.isFinished() ? TOUCH_STATE_REST : TOUCH_STATE_SCROLLING;
//				break;
//
//			case MotionEvent.ACTION_CANCEL:
//			case MotionEvent.ACTION_UP:
//				mTouchState = TOUCH_STATE_REST;
//				break;
//		}
//
//		if (mTouchState != TOUCH_STATE_REST)
//		{
//			Log.i("mTouchState != TOUCH_STATE_REST", " return true");
//		}
//
//		return mTouchState != TOUCH_STATE_REST;
		return false;
	}
	
	private boolean IsCanMove(int deltaX)
	{
	
		if (getScrollX() <= 0 && deltaX < 0 )
		{
			return false;
		}
		
		if  (getScrollX() >=  (getChildCount() - 1) * getWidth() && deltaX > 0)
		{
			return false;
		}
			
		
		return true;
	}
	
	public void SetOnViewChangeListener(OnViewChangeListener listener)
	{
		mOnViewChangeListener = listener;
	}

}
